<script>
  var name = 'Nicholas'; 
  let age = 26;
</script>

<script>
  // Suppose this script is unsure about what has already been declared in the page. 
  // It will assume variables have not been declared.

  var name = 'Matt';
  // No problems here, since this will be handled as a single hoisted declaration.
  // There is no need to check if it was previously declared.

  let age = 36;
  // This will throw an error when 'age' has already been declared. 
</script> 
